Fibrous structures formed from heat fused, discrete length staple fibers of standard cylindrical geometry are generally known. In the past, such fibrous structures have been formed by blending staple fibers of a first polymer with staple fibers of a second fiber having a lower melting point across its surface and thereafter applying heat and pressure to force point bonding between the fibers. The second fiber may be of substantially uniform composition through its cross-section or may be of a so called bicomponent construction wherein a sheath of a lower melting point polymer is wrapped around a core of a compatible higher melting point polymer.
It has been proposed to form tape structures from polypropylene film that is coated with a layer of propylene copolymer including ethylene units such that the coating has a lower softening point than the core. Such tape structures are disclosed, for example, in U.S. Pat. No. 5,578,370, the teachings of which are hereby incorporated by reference in their entirety. U.S. Patent Application 2004/0242103A1 (incorporated by reference) has also proposed to form monoaxially drawn tape structures characterized by substantial draw ratios and incorporating a central layer of a polyolefin with one or two covering layers of a polyolefin from the same class as the central layer. The DSC melting point of the outer layers is lower than that of the central layer to facilitate heat bonding.